Division of Pathology, Centro di Riferimento Oncologico Aviano, Istituto Nazionale Tumori, IRCCS, 33081 Aviano, Italy.
Hum Pathol. 2012 May;43(5):619-28. doi: 10.1016/j.humpath.2011.09.002. Epub 2011 Dec 29.
The 2008 WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues has addressed the problem of intrafollicular neoplasia/"in situ" lesion for follicular lymphoma. The concept of intrafollicular neoplasia has also been proposed for other lymphomas in which the putative normal counterpart of the tumor cell is located in the germinal center or the mantle zone or the marginal zone of the follicle. However, unlike in situ follicular lymphoma, the precise histologic definition of this early lesion for other lymphomas is still lacking. When applied to nodular lymphocyte predominant Hodgkin lymphoma, another germinal center-derived lymphoma, "intrafollicular neoplasia" may be regarded as a neoplasia at an early stage of development, such as in situ follicular lymphoma. Interestingly, this early lesion can be observed in lymph nodes that otherwise show the most common nodular involvement by nodular lymphocyte predominant Hodgkin lymphoma. The recognition of intrafollicular neoplasia is based on the identification of typical, strongly stained BCL6+, lymphocyte predominant tumor cells located within altered follicles with a recognizable germinal center. Lymphocyte predominant tumor cells, surrounded by rosetting PD1+ T cells, reside in an environment reminiscent of a secondary follicle. Intrafollicular neoplasia in nodular lymphocyte predominant Hodgkin lymphoma is correctly identifiable based on immunohistochemical recognition of the CD23+ meshwork of follicular dendritic cells surrounded by an outer zone containing immunoglobulin D+ B cells. This immunoarchitectural pattern, highlighting the intrafollicular involvement by the neoplasia, is of great utility for diagnosis. An appropriate immunohistochemical characterization for diagnosis should include lymphocyte predominant (BCL6 and CD20) and microenvironmental (CD23, immunoglobulin D, and PD1) cell markers.
2008 年世界卫生组织造血和淋巴组织肿瘤分类解决了滤泡性淋巴瘤的滤泡内肿瘤/原位病变问题。滤泡内肿瘤的概念也被提出用于其他淋巴瘤，其中肿瘤细胞的假定正常对应物位于生发中心、套区或滤泡的边缘区。然而，与滤泡性淋巴瘤原位病变不同，其他淋巴瘤这种早期病变的确切组织学定义仍然缺乏。当应用于结节性淋巴细胞为主型霍奇金淋巴瘤时，另一种生发中心来源的淋巴瘤，“滤泡内肿瘤”可能被视为发育早期的肿瘤，如滤泡性淋巴瘤原位病变。有趣的是，这种早期病变可以在其他表现为结节性淋巴细胞为主型霍奇金淋巴瘤最常见结节性受累的淋巴结中观察到。滤泡内肿瘤的识别基于识别位于具有可识别生发中心的改变滤泡内的典型、强烈染色的 BCL6+、淋巴细胞为主的肿瘤细胞。被玫瑰花结 PD1+T 细胞包围的淋巴细胞为主的肿瘤细胞位于类似于次级滤泡的环境中。结节性淋巴细胞为主型霍奇金淋巴瘤中的滤泡内肿瘤可以通过免疫组织化学识别 CD23+滤泡树突状细胞的网状结构来正确识别，该结构被含有免疫球蛋白 D+B 细胞的外区包围。这种免疫结构模式突出了肿瘤的滤泡内受累，对于诊断非常有用。用于诊断的适当免疫组织化学特征应包括淋巴细胞为主（BCL6 和 CD20）和微环境（CD23、免疫球蛋白 D 和 PD1）细胞标志物。
